Abstract:
Under global warming, the climatic features of the rainy season are crucial to understanding the regional water cycle. Based on daily meteorological data from 101 sites over the Qinghai-Xizang Plateau from 1980 to 2019, we investigate climatic features in the rainy season, including the onset and end dates, duration, precipitation amount, and precipitation intensity, which is refered to the “China Rainy Season Monitoring Indicators—Rainy Season in Southwest”. The climatic characteristics of these factors and their regional differences were also analyzed. The following results were found: (1) The earliest (latest) onset of the rainy season over the Qinghai-Xizang Plateau is 2 May (19 June), gradually extending from east to west. The earliest (latest) end date of the rainy season is15 September (20 October), quickly ending from west to east, while the rainy season lasts for more than five months (less than three months) in the eastern (western) Qinghai-Xizang Plateau. (2) The interannual variations of onset dates and duration of the rainy season over the Qinghai-Xizang Plateau show a consistent spatial pattern, with relatively high values in the southeastern Qinghai-Xizang Plateau and Qaidam Basin. The interannual variation in the end dates of the rainy season is significantly small and that of precipitation is large, with the coincidence of the small former and the large later. (3) The onset date of the rainy season is more closely connected to its duration and precipitation amounts than to the end date. Specifically, an early (late) onset of the rainy season corresponds to a longer (shorter) duration and a higher (lower) precipitation amount. (4) The spatial pattern of rainy season over the Qinghai-Xizang Plateau features significantly north−south reverse, which is divided by the Tanggula Mountains (32.5° N). The south Qinghai-Xizang Plateau presents a later onset date, an earlier end date, a shorter duration, higher precipitation amounts, and greater precipitation intensity than that on the north Qinghai-Xizang Plateau.